Moll's vanity and greed are the main focus of the characterization in the novel. Quite early in her life she has an all-consuming desire to become a gentlewoman, a fact which was almost impossible for a lower-class woman because of the rigid class lines in England in that period. In a sense this desire throughout her life leads her into one misadventure after another.

Moll's genteel education is beyond her "station in life" with its concentration on music, French and writing rather than on a vocational skill that could help her earn a living. To compound Moll's problem, she is excessively vain. From the time she is ten she hears herself referred to as pretty. Moll's initial seduction is as much the result of her vanity as the fine words and devious ways of the elder brother. She indicates, "That gentleman had now fired his inclinations as much as he had my vanity."

Defoe reveals Moll as an avaricious woman who sees people, even her own children, in economic terms. Gold is the thing that motivates the bulk of her actions, and the only deficits she experiences are emotional ones.

Defoe clearly reveals the difference between Moll's recurrent but passing misgivings about her degeneration, and her real repentance. Her repeated "considerations" but continuing "adventures" show Moll as essentially untouched emotionally and morally.

None of the other characters are vividly portrayed in this book. They simply serve to reflect Moll. They are a backdrop to her actions. In fact, these other characters seem rather unreal, shallow representations often remaining nameless, such as the elder brother, the "nurse," the governess, the Captain's widow, the ship's captain. Moll's mother is another nameless character. Most of her husbands and lovers are known by their trades or station in life such as the draper, the gentleman at Bath, the Lancashire husband.